Hidition Custom IEM Viento (VientoB) Review

240513 – Repost from a My Korean Blog

After a long, long wait, my custom IEMs have finally been completed.

So I’ll leave a short note here to commemorate the occasion.

Traveling all the way from Gyeongnam to HiDition’s headquarters in Incheon would have been too far, so I had my ear impressions taken at the Phonak Hearing Aid center in Seomyeon, Busan. I booked an appointment in advance, and they examined the details of the impression’s surface and took a few more until it looked right. Honestly, at that time I thought, “Once the impressions go from Busan to Incheon, they’ll probably make the molds quickly, right?

For the custom order, I chose HiDition’s Viento B version. The R version has a switch to adjust bass and treble but comes with an extra charge. Since I rely heavily on DSP, I saw no need to purchase the R version, so I went with B.

If it were possible, I would have liked a custom build with the 14.5mm planar second-generation driver, but after checking everywhere domestically and abroad, I couldn’t find any maker I liked or that met the specs (or their measurements and distortion figures were already off). I also considered importing C-Audio’s Kaguya model from China, but the messy distortion characteristic of C-Audio seems present across all their series.

Even taking into account that I applied a ±10 dB bass/high tilt to approximate a real music signal, it still felt excessive—distortion easily exceeded the 1% range.

That’s why I chose the domestic HiDition maker, and the waiting began.

As I later discovered, if you select the special production option (around 220,000 KRW) when ordering, you can drastically shorten the lead time—from about five weeks down to roughly one week.

By the company’s receipt date, it took exactly one month; from the Busan Seomyeon impression date, it was completed after approximately one month and five days.

Receiving the finished IEMs wasn’t entirely smooth either. I couldn’t tolerate another weekend wait for courier delivery, so I asked HiDition for understanding and used a quick-service pickup in Incheon. From there, I sent it via express bus cargo to Jinju in Gyeongnam, allowing me to receive it the same day.

When I opened the box, there was a sleek black pouch, and inside were the custom-made IEMs with their serial information, along with a small cleaning brush. It might seem minimal, but the package is neatly arranged and more than adequate.

I’ve used various IEMs, including the Etymotic ER2XR, which requires deep insertion. The comfort of the Etymotic is truly terrible—it feels more like torture than listening to music. Even when inserting a microphone all the way to the second bend for binaural in-ear measurements, it doesn’t cause that level of pain. I suspect the characteristic material of the triple-flange tip may be adding extra irritation inside the ear canal.

You can see the exact shape of my ear canal reproduced in the shell. When inserting them, you just twist gently clockwise, and they smoothly slide in, seating themselves right before the second bend.

Surprisingly, they’re comfortable. Of course, compared to shallow-fit or open designs like Apple EarPods, Final E500, Westone W10, or Sennheiser IE200, it’s naturally a different experience. Because the custom shell fills the canal precisely, you do sense something in your ear, but it fits so well that it’s not unpleasant at all. I hardly notice that they’re in place, though there are moments that remind me of the softness of something like Hollox’s silicone nozzle.

The skin just before the second bend in the canal is inevitably sensitive to irritation. And while the hard resin shell doesn’t scrape like an Etymotic tip might, frequent insertion and removal could still cause some irritation over time. Other than that, the fit is perfect.

They recommended taking the impression with my mouth closed, and I’m glad I did. Reading online, I’ve seen cases—both domestic and abroad—where people feel severe pressure when wearing custom IEMs. For singers, it makes sense to take impressions with the mouth slightly open or biting something, since they sing with an open mouth. But for listening purposes, filling the ear canal fully as in a closed-mouth impression inevitably causes some discomfort if not done correctly.

Overall, though, having the impression taken with my mouth closed seems to have ensured a comfortable result.

Just like the experience when taking ear impressions, the moment you insert the IEM by twisting it clockwise, it becomes as quiet as being in an anechoic chamber.

I can only hear my heartbeat. The isolation is on a level incomparable to that from typical ear tips. (It might be different with foam tips instead of silicone tips, but I personally don’t prefer foam.)

Isolation is extremely important when listening to music. You can achieve a much greater dynamic range compared to your usual listening volume.

And you can immediately notice the increased insertion depth. As mentioned above, anyone who has inserted a microphone for binaural measurements up to just before the second bend (such as Etymotic users) will recognize that exact sensation of stimulation in that area. The IEM is precisely crafted to insert as deeply as it can comfortably go.

As a result, you can distinctly feel that the resonance shifts to higher frequencies. (In practice, resonance isn’t much of an issue since I use DSP processing for music listening, but having a stable and balanced response is always advantageous.)

I measured using a loaned 711-clone coupler sealed with Blu-Tack. Since this isn’t a 5128 coupler, GRAS rig, or BK preamp setup, the measurements aren’t highly reliable, but at least relative comparisons among my IEMs are possible.

Here are the frequency response and phase of the Viento. Above 8 kHz can be ignored due to the 711’s low reliability in that range. Even though I sealed it with Blu-Tack, custom IEMs are inherently less compatible with the measurement rig, so you have to interpret only the general trends. (Even GRAS or 5128 frequency-response measurements don’t perfectly reflect exactly what happens in the ear canal.)

Overall, there don’t appear to be any major issues.

Of course, HiDition provides measurement data for each individual IEM. For convenience, I displayed the same graphs in REW, using DF and inverse compensation so that they reflect the same uncorrected-target measurements we typically see. The left-right matching is excellent.

These are the FR measurements remaining after several attempts sealing with Blu-Tack, and it seems they’re related to the fit.

The first time I inserted them, the bass through the highest treble all sounded fine, but the second time, when I roughly inserted them and listened, the bass seemed to disappear—and that is reflected directly in the measurements.

These are THD measurements using 94 dB and 104 dB stepped sine signals. It would be unrealistic to expect performance on par with planar or high-end dynamic drivers, but for a BA it’s quite respectable. More importantly, the real question is whether you can actually hear distortion, and the Viento handled sound pressure levels above 90–100 dB without issues. The MP145’s distortion performance also holds up remarkably well.

Still, the key takeaway is that the first and second times I listened to the Viento, I thought, “I could probably get rid of my MP145 now.” That alone is basically game over. My original plan was to use EarPods for casual background music, the Viento for lighter music listening, and the MP145 when I wanted really intense, ear-bursting levels… but the Viento is so unexpectedly good that I’m honestly a bit unsettled.

Even here, the limitations of multi-BA drivers become gradually apparent. I compared the MP145 and the Viento by playing a two-tone signal at 60 Hz and 500 Hz with a 4:1 amplitude ratio.

This was from when I compared the MP145 with Apple EarPods. I should have taken multitone measurements according to EIA-426B or based on a music-spectrum profile, but I totally forgot.

Honestly, I’m not a big fan of the sound of IEMs or headphones by themselves. People debate preferences like Harman target vs. diffuse-field target, but once you remove crosstalk and go into a raw binaural state, the tonal balance inevitably differs from how we hear speakers or natural sounds—there’s an inherent strangeness.

Beyond distortion artifacts, there are many limitations and shortcomings, so when we compare devices by listening, we really end up relying on our brain’s own corrections. What happens in the ear canal is different, plus we don’t normally listen with only one ear at a time, so that unfamiliar tonal balance combined with our prior listening experiences already overloads the brain.

That’s why true spatial impression can’t really exist with IEMs or headphones: there are no definitive external cues to anchor a space. Yet many people still describe some as “wider” or “narrower.” Studies have shown that in a fully crosstalk-free binaural condition, the brain can get confused and create the illusion of a wider space.

Thus, two people listening to the same IEM or headphone response might disagree: one person may feel the stimulus from the FR response and the earcup pressure makes it seem wider, while another feels the opposite. For this reason, when doing blind listening tests on IEMs, I use personalized extracted crosstalk information. You could use crossfeed to mix channels, but to be as accurate as possible and minimize brain correction and confusion, I apply individualized ITD delays around 220–250 µs.

With that approach, every IEM or headphone begins to sound “normal,” letting you hear the true character of the IEM or headphone without your brain overcompensating.

And the Viento’s sound is quite surprising—it’s very unremarkable in a good way. I’m not sure if “unremarkable” is the right word for a pair of IEMs costing nearly 1,000 USD, but perhaps being unremarkable is both simple and hard to achieve. If it corresponds to the average of a natural HRTF, it should sound unremarkable; if not, it’s just artificially boosted or stretched in certain bands to make something stand out.

You can feel there’s still headroom beyond 8 kHz, and the bass is solid. It follows EQ adjustments well. Compared to the second-generation planar bass, it has a bit of that “BA” character, but across all other bands, it’s the cleanest IEM I’ve heard so far.

And here are my impressions when listening with the BRIR setup measured in my usual real-ear measurement.

From the first listen, I knew this was it. Personalized measurements with personalized IEMs… there’s nothing more to add.

However, I had a concern even before ordering custom IEMs. I experienced this strongly with deep-insertion Etymotic tips.

Off-the-shelf IEMs and headphones each pump out whichever “crafted” sound they aim for. In contrast, BRIR assumes a target sound as the reference “1,” and IEMs/headphones serve merely as playback devices trying to reproduce that “1.” Most IEMs do this reasonably well, but Etymotic felt like: if there’s 300 ms of reverb, it arbitrarily chops it down to around 100 ms—essentially a form of modulation or distortion in another sense.

I worried that, with deep insertion, the sound reaching my eardrum would be so close and the successive impulses so disorienting that my brain might get confused. Because of that, I paid special attention to this aspect with the custom IEMs.

The Viento, however, had absolutely no issues. It seems Etymotic simply lacks the playback capability for this. Even at high sound-pressure environments (Topping L70 + high gain + 4.4 mm balanced connection), it reproduced cleanly without any problems. Under near-anechoic conditions plus reflections plus XTC, even the unconventional impulses in a 90°-side binaural XTC scenario sounded incredibly appealing. It felt simultaneously “IEM-like,” “headphone-like,” and “speaker-like”—it was space and sound itself.

If a device can reproduce XTC as intended by XTC, it passes the BRIR playback audition stage with flying colors.

In conclusion: it’s excellent! Anyone who enjoys IEMs should consider getting a custom fit at least once. You won’t regret it.

Below are the links to the original Korean blog posts.

하이디션 커스텀이어폰 비엔토(VientoB) 후기 Hidition Custom IEM Viento (VientoB) Review

편한 이어폰... 외이도염, 그리고 하이디션의 비엔토? Comfortable IEM… Otitis Externa, and HiDition’s Viento?

가벼운 헤드폰, 코스Koss KSC75 짧은후기 Lightweight Headphones: Koss KSC75 Short Review

오픈형 이어폰은 돌고돌아 이어팟 (feat. 피오 ff1) The craving for open earphones always comes back to Apple Earpod

이어폰 2핀단자가 헐렁거릴때 When the 2-Pin Connector of an IEM Becomes Loose

삼성 갤럭시 버즈3 프로 짧은후기 - 유선의종말? Samsung Galaxy Buds3 Pro Short Review – The End of Wired Audio?

Equalizer APO을 위한 돌비 업믹싱 Dolby Upmixing for Equalizer APO

스피커가 사라진다, 우리가 실제로 듣고있던건 뭘까-BacchORC의 목적 Speakers Disappear: What Were We Actually Hearing? – The Purpose of BacchORC

바이노럴 가상화, 외부화에 대한 내용들 요약 Summary of Binaural Virtualization and Externalization